Harness for supporting high pressure arc discharge tube within outer envelope, and lamp formed thereby



June 18, 1963 D HARNESS FOR SUPPORTI N OUTER ENVELOPE, AND

FORMED THEREBY TUBE WITHI LAMP Filed Dec. 19, 1960 ARGE . S. GUSTIN NGHIGH PRESSURE ARC DISCH 2 Sheets-Sheet 1 DANIEL S. GUSTIN INVENTOR.

A TORNEY June 18, 1963 D. s. GUSTIN 3,094,640

HARNESS FOR SUPPORTING HIGH PRESSURE ARC DISCHARGE TUBE WITHIN OUTERENVELOPE, AND LAMP FORMED THEREBY Filed Dec. 19, 1960 2 Sheets-Sheet 2DANIEL S. GUSTIN INVENTOR.

AT ORNEY United States Patent HARNESS FOR SUPPORTING HIGH PRESSURE ARCDISCHARGE TUBE WITHIN OUTER ENVE- LOPE, AND LAMP FORMED THEREBY DanielS. Gustin, Londonderry, N .H., assignor to Sylvania Electric ProductsInc., a corporation of Delaware Filed Dec. 19, 1960, Ser. No. 76,799 12Claims. (Cl. 313-25) This invention relates to high-pressure, electricdischarge devices and more particularly to an improved arc tube supportgenerally called a harness.

High pressure electric discharge lamps are well known and are described,for example, in United States Patent 2,901,647 to M. J. Thomas et al.Such lamps comprise an inner arc tube mounted in a surrounding,light-transmitting, outer envelope by an intermediate supportingharness. The outer envelope may be left clear or may be coated withphosphor material as desired.

In the manufacture of such lampsit has been found that one of the moretroublesome steps is the sub-assembly operation of constructing theharness which holds the arc tube in the outer envelope. This harnessgenerally comprises a large number of structurally stable bent wires andmetal supporting brackets which are spot welded together in separatesteps. Each spot weld affords an opportunity for imperfection in lampconstruction and accordingly it is desirable to eliminate such wires,brackets, and spot welds. Furthermore, it is desirable to prepare asmuch as practical of the construction in a unitary stamped-out design.

For such reasons, attempts have been made to use a single-wire arc tubesupport, wherein a metal wire is suitably bent and shaped to support thearc tube in the bulbous envelope. Such constructions, however, are notentirely acceptable since there is not significant diminution of thenumber of spot welds required to fabricate the harness nor does itproduce a structurally stable device.

Another proposed harness comprises a pair of similar stamped-out supportmembers, which are spot welded in numerous places after the arc tube hasbeen positioned between suitably shaped cross arms. This design was notentirely satisfactory since the number of spot welds is not appreciablyreduced. Furthermore, it makes no provision for accommodating smallvariations in lengths from tube to tube.

When prefabricating a lamp using the unitary harness as proposed in thisinvention there are no spot welds utilized to prepare the harnessitself; only a few are necessary for the attachment of the variouselectrical contacts. Furthermore, the harness is shaped to each individual arc tube and small difierences in the length of each tube maybe compensated without any difficulty.

Accordingly, an object of the present invention is the fabrication of astructurally stable, unitary, stamped-out arc tube harness requiring aminimum number of welds.

An advantage of this invention is that the number of spot weldsnecessary has been reduced from twenty-two to six, thus reducing themanual labor required to fabricate the arc tube supports.

Another advantage of this invention is the ease and cheapness ofmounting the arc tube and preparing the harness.

Other objects and advantages of this invention will become apparent tothose skilled in the art upon reading the following specification whentaken in conjunction with the accompanying drawings.

FIGURE 1 is an elevation view of a high pressure discharge lamp whereinthe arc tube harness is shown positioned within a glass envelope.

FIGURE 2 is an illustration of the stamped arc tube ice harness of thisinvention before the various folding operations.

FIGURE 3 is a top plan view taken along the lines 33 of FIGURE 4. Inthis figure the bulbous glass envelope surrounding the arc tube is notshown.

FIGURE 4 is an illustration of a side elevational view of the unitaryarc tube harness according to this invention, taken along the lines 44of FIGURE 3.

In each of the figures, similar numerical designation will connotesimilar elements.

The invention will be illustrated with reference to a high pressuremercury vapor lamp since it is generally used in such construction, butthe harness can also be used in other similar devices.

As will be seen in FIGURE 1, the unitary harness 1 for supporting thearc tube 15 is positioned generally in the central portion of thebulbous envelope 3. In order to obtain the maximum efliciency for thelamp, it is conventional practice to axially position the arc tube 15 inthe bulbous envelope. However, if it is desired to rearrange thepositioning, this axial relationship may be changed. The harness '1comprises the two elongated, spaced struts 5 and 7. In most cases thestruts 5, 7 can be substantially parallel, but other configurations canbe used, if desired. The supporting cross arms 9 and 11 extend from onestrut to the other and space them apart. Tabs attached to these armshold the arc tube 15 in the bulbous envelope 3 in a generally co-axialposition. Tabs 17 and 18 which extend from the upper supporting crossarm 9 serve as the upper attaching support for the arc tube. Extendingfrom the lower supporting cross arm 11 is a generally U-shaped tab 19which serves as the lower attaching support for the arc tube. These tabsare folded over the flattened end portions 61 of the arc tube andrigidly attach the arc tube to the harness. Also provided on each of thesupporting cross arms are the stamped out guides 21 which are adapted toengage the sides of the pinched portions 61 of the arc tube and preventits lateral movement in the harness. The electrical contact cross arm 23extends between struts 5 and 7 and is positioned above the uppersupporting cross arm 9. One electrode or" the arc tube is affixed tothis cross arm. Generally the lead-in Wire 25 may be inserted in asuitable stamped portion 27. Although no welding is generally necessaryfor this attachment, it may be utilized if desired. In addition toproviding an electrical contact, the cross arm 23 also increases thestability of the harness in the lamp and will provide transverse supportfor the upper portion of struts 5 and 7. Although the cross. arm 23 isshown as a horizontal bar, it is apparent that it may haveother shapes.

The resilient bumpers or bulb spacers 29, 28, 6 and 12 are in contactwith the upper tubular portion of the glass envelope 3. These bumpersmaintain co-axial positioning of the harness and are tube even when thelamp is subjected to shocks such as shaking and jarring. It is highlyadvantageous to have such resilient spacers in the lamp, and it is-quiteimportant that they are a unitary part of the stamped-out harness. Priorattempts to fabricate a stamped-out harness have not provided suchintegral resilient spacers and it was necessary to rigidly position theupper portion of the harness in a protuberance in the glass envelope. Itis apparent, however, that if it is desired to have an outer bulbousenvelope of different construction, the harness may be adapted to berigidly placed in the envelope without these bulb spacers. This type ofpositioning is obtained by eliminating the bulb spacers and extendingthe upper portion of the electrical contact cross arm 23 to generallyfit in a protuberance in the envelope.

To protect the resistor 37 and diflfuse heat from the ends of the lamp,the heat shield 30 is positioned below the lower cross arm 11. Anaperture 31 is provided in the central portion of the heat shield 30 sothat the lead-in wires 33 and 35 will not contact the harness. Throughthe use of this aperture conventional tubular glass insulators aroundthe wires 33 and 35 may be eliminated. If additional insulation isdesired, however, they may be added.

In the lower portion of the unitary harness a cross arm 26 is providedto position the lamp in the bulbous envelope. The structurally stablelead-in wire 39 is inserted into the stamped-out portion 40 of thepositioning cross arm 26. Spot welding may be utilized, if desired. Thisconstruction will insure the uniform positioning of the harness in thelamp and will provide a structurally stable base for the assembly. If itis desired to rotate the harness 90 about its longitudinal axis, thepositioning of the stamped-out portion 40 may be offset from theco-axial so that there will be no electrical contact between the leadinwire 43 and the positioning cross arm 26.

In the sealing operations it is general practice to have gases pass inand out of the aperture 49 of the re-entrant stem press 46. A bafile isprovided to prevent gases from directly contacting the bulbous glassenvelope 3 as a stream and dislodging some of the coated phosphor. Thisbatiie is positioned directly in front of the re-entrant aperture 49 andcomprises the plate 45 and the stem 47. The stem 47 is bent around sothat the plate may be placed directly in front of the aperture 49.

The remainder of the lamp is of substantially conventional construction.The glass of the envelope 3 is sealed to the threaded cap 53, which inturn is insulated from the electrical contact 55 by means of theinsulating ring 57. In the same manner the arc tube 15 is of conventional construction and comprises a light-transmitting envelope 59,normally fabricated of quartz, or similar heat resisting material. Seals61 are conventionally provided at either end of the :arc tube. Theseseals may be either flattened, pinched portions or may assume agenerally cylindrical shape. In the case of a seal having a generallycylindrical shape, the tabs 17 and the U-sha-ped support member 19 maybe modified by providing elongations in order to suitably support thearc tube. Ribbon sealed conductors are sealed in each of the pinched orsealed portions 61. These conductors are attached at one end to each ofthe lead-in wires 35, 33 and 25. At the other end of the ribbonconductor the conventional electrodes 34 and starting electrode 36 areattached. For purposes of electron emission a thorium sliver isdesirably included as part of the electrodes 34, which may be fabricatedof tungsten for example, by conventional electrode construction methods.The are tube contains a selected charge of mercury and an inertionizable gas such as and mm. of mercury of argon.

The metal used in the unitary harness should be strong, durable and heatresistant; it may be, for example, sheet stock such as 10 milnickel-plated iron. Although this metal is quite strong in itself, it isoften desirable to strengthen the harness by adding indentations 10' and22. These indentations may be placed elsewhere on the harness where itis desired to have additional stability.

Reference is now made to FIGURE '2 which shows the stamped harness priorto its being bent into shape. The struts 5 and 7 have attachedstiffening portions 4 and 8 which were adapted to be bent to an angle ofabout 90 with respect .to the struts. In this manner, althoughrelatively thin and inexpensive sheet stock is used, the necessarystructural stability is obtained. The upper supporting cross arm 9 hastwo tabs '17 and 18 extending from the upper portion thereof. These tabsare adapted to be bent around the pinched portion of the arc tube. Twotabs are used so that the lead-in wire 25 (as shown in FIGURE 1) mayextend upwardly from the arc tube and no changes need to be made in thearc tube design. Two stamped-out guide means 21 are provided on thecross arm 9. These guides may be bent to an angle of about with respectto the supporting cross arm to provide lateral support for the arc tube.

A U-shaped tab 19 extends from the lower cross arm 11. In the centralportion of this tab an aperture 32 is provided for the lead-in wires ofthe arc tube. The Wires 33 and 35 must be electrically insulated fromthe harness, since the harness is used as a means for conducting electricity to the other electrode. Two additional guide means 21 areprovided on the lower cross arm 21; when bent out in the appropriatebending operation these guides will inhibit the lateral movement of theare tube in the harness.

The heat shield 30 is positioned beneath the cross arm 11. An aperture 31 is stamped in the central portion thereof for the passage ofappropriate lead-in wires. The shield 30 is joined to the struts 5 and 7and the supporting cross arm 11 by means of the bendable portion 14. Theremainder of the heat shield is stamped through so that it may be bentto an angle of about 90, with respect to the cross arm.

Above the cross arm 9 is the electrical contact cross arm 23 having astamped aperture 27. Indentations 10 may be added to improve stability.The stamped aperture is provided to permit the insertion of the lead-inwire 25 of the are tube (shown in FIGURE 1). Above the electricalcontact cross arm is a series of four fingers or bumpers 12, 6, 28 and29'. The bumpers attached to the same strut are bent in oppositedirections to a position of about 90". As noted previously if it isdesired to have a rigid construction rather than the resilientconstruction of this invention this entire upper portion of the harness,including the electrical contact 23, may be redesigned.

In the lower portion of the unitary harness the plate 45 is shownattached to stem 47. To fabricate the harness, plate 45 is bent 90 withrespect to stem 47. The stem 47 is then angled back to place the plate45 in front of the ire-entrant hole 41 (shown in FIGURE 1).

Thus the unitary harness is made of a single metal sheet, properlystamped and so designed whereby the ruggedness of previous wireharnesses is exceeded, and substantial savings in manual labor arerealized. Furthermore, the number of spot welds needed to fabricate alamp is markedly reduced.

FIGURES 3 and 4 are showings of the harness after the bendable portionsare aligned in their appropriate positions. As is seen each of bumpers12, 98, 6 and 28 are bent 90 in opposite directions so that they are insubstantially parallel alignment. The heat shield 30 is bent upwardlyabout 90 and the plate 45 is bent 90 with the stem 47 helically bent toproperly position it in front of the re-entrant hole.

In assembling the lamp, a suitable are tube 59 is placed on the crossarms, the guides 21 having previously been bent :out and the U-shapedtab 19 bent around the pinched portion 61. The lead-in wires 33 and 35are placed through the aperture 32 in the U-shaped tab 19. After properpositioning is assured, the tabs 17' and 18 are bent around the upperportion 61 of the arc tube. This bending after positioning of the arctube is quite important, since small differences in linear length of thearc tube will be compensated for and a rigid attachment of the arc tubeto the harness will be insured. The electrical lead 25 is placed in theaperture 27 provided in the electrical contact cross arm 23 and spotwelded if desired. Although an aperture is shown, this lead may bedirectly spot welded to the electrical contact cross-arm if desired.After the arc tube is positioned the electrical leads 33 are welded tolead-in wire 43. Electrical contact 55 has previously been welded tolead-in wire 43 which in turn is welded to the heat shield 30. Theharness with the stem is then mounted in the bulbous envelope byconventional means. The cap 53 with insulation 57 and electrical contact55 are sealed to the bulbous envelope and a finished lamp is produced.

It is apparent that changes and modifications may be made within thescope of the instant invention. It is my intent, however, to be limitedonly by the scope of the appended claims.

I claim:

1. A unitary harness for holding an arc tube comprising a single sheetmetal frame stamped and shaped into a pair of elongated struts spacedfrom each other, a pair of supporting cross arms positioned transverselybetween said struts, means for attaching said arc tube to saidsupporting cross arms and means to position said harness in a bulbousenvelope.

2. A unitary harness for holding an arc tube comprising a single sheetmetal frame stamped and shaped into a pair of elongated struts spacedfrom each other, a pair of supporting cross arms positioned transverselybetween said struts, means for attaching the ends of said arc tube tosaid cross arms, said means comprising tabs extending from saidsupporting cross arms and adapted to fold about said ends and means toposition said harness within a bulbous envelope.

3. A unitary harness for holding an arc tube comprising a single sheetmetal frame stamped and shaped into a pair of elongated, spaced-apartstruts, a pair of supporting cross arms transversely positioned betweensaid struts, means for attaching saidare tube to said supporting crossarms, a heat shield positioned between said struts and below the lowerof said supporting cross arms, means to position said harness within abulbous envelope.

4. The unitary harness according to claim 3 wherein a means forming anaperture is positioned in the central portion of said heat shield.

5. A unitary harness for holding an arc tube comprising a single sheetmetal frame stamped and shaped into a pair of elongated struts spacedfrom each other, a pair of supporting cross arms positioned transverselybetween said parallel struts, means for attaching said are tube to saidsupporting cross arms, an electrical contact cross arm positionedbetween said struts and above the upper of said supporting cross arms,said are tube adapted to be in electrical contact with said electricalcontact cross arm and means to position said harness within a bulbousenvelope.

6. A unitary harness for holding an arc tube comprising a single sheetmetal frame stamped and shaped into a pair of elongated, spaced apartstruts, elongated spaced apart stiffening means attached to each of saidstruts and in an angular relation therewith, a pair of spaced apartsupporting cross arms transversely positioned between said struts, meansfor attaching said are tube to said supporting cross arms, and means toposition said harness in a bulbous envelope.

7. A unitary harness adapted to hold an arc tube comprising a singlesheet metal frame stamped and shaped into a pair of elongated strutsspaced from each other, a pair of supporting cross arms positionedtransversely between said struts, means to aflix the ends of said aretube to said cross arms, resilient bulb spacers attached to each of saidstruts and being positioned above the upper of said supporting crossarms and means to position said harness in said envelope.

8. A unitary harness adapted to hold an arc tube comprising a singlesheet metal frame stamped and shaped into a pair of elongated, spacedapart struts, a pair of supporting cross arms positioned transverselybetween said struts, means to afiix said are tube to said supportingcross arms, a re-entrant aperture baffle attached to the lower portionof said unitary harness below the lower of said supporting cross arms,and means to position said harness within a generally bulbous envelope.

9. A unitary harness for supporting an arc tube having flattened endportions comprising, a single sheet metal frame stamped and shaped intoa pair of elongated, substantially parallel struts spaced from eachother, a pair of supporting cross arms transversely positioned betweensaid struts, means to affix the ends of said are tube to said supportingcross arms said means comprising tabs extending from said supportingcross arms adapted to be folded around said flattened ends, anelectrical contact cross arm positioned transversely between said strutsabove the upper of said supporting cross arms, a heat shield below thelower of said cross arms attached to and positioned between said struts,a re-entrant aperture bafile attached to the lower portion of saidharness below the lower of said supporting cross arms, stiffening meansattached to each of said struts positioned substantially parallelthereto and in an angular relationship therewith, resilient bulb spacersextending transversely from each of said struts, and means to positionsaid harness within a generally bulbous envelope.

10. A high pressure discharge lamp comprising an arc tube, a transparentouter bulbous envelope around said tube but spaced therefrom, a unitaryharness fabricated of a single stamped and shaped sheet metal frame forholding said tube, said harness comprising a pair of elongated strutsspaced from each other, a pair of supporting cross arms positionedtransversely between said struts, means for attaching said tube to saidsupporting cross arms, and means to position said harness in saidbulbous envelope.

'11. A high pressure discharge lamp comprising, an arc tube, atransparent outer bulbous envelope around said tube but spacedtherefrom, a unitary harness fabricated of a single stamped and shapedsheet metal frame for holding said tube, said harness comprising a pairof elongated struts spaced from each other, a pair of supporting crossarms transversely positioned between said struts, means for attachingsaid arc tube to said supporting cross arms comprising tabs extendingfrom said supporting cross arms and adapted to fold about the ends ofsaid are tube, and means to position said harness within said bulbousenvelope.

12. A high pressure discharge lamp comprising, an arc tube havingflattened end portions, a transparent outer bulbous envelope around saidtube but spaced therefrom, a unitary harness fabricated of a singlestamped and shaped sheet metal frame for supporting said are tubecomprising a pair of elongated, substantially parallel struts spacedfrom each other, a pair of supporting cross arms positioned between saidstruts, means to aflix the ends of said are tube to said supportingcross arms, said means comprising tabs extending from said supportingcross arms adapted to be folded around said flattened ends, anelectrical contact cross arm positioned transversely between said strutsabove the upper of said supporting 'cross arms, a heat shield below thelower of said cross arms attached to and positioned between said struts,a re-entrant aperture bafile attached to a positioning cross arm in thelower portion of said harness, stiffening means attached to each of saidstruts positioned substantially parallel thereto and in angularrelationship therewith.

References Cited in the file of this patent UNITED STATES PATENTS2,748,306 Thorington May 29, ,1956 2,749,462 Kenty June 5, 19562,802,961 Jenne Aug. 13, 1957 2,951,959 Fraser Sept. 6, 1960

1. A UNITARY HARNESS FOR HOLDING AN ARC TUBE COMPRISING A SINGLE SHEETMETAL FRAME STAMPED AND SHAPED INTO A PAIR OF ELONGATED STRUTS SPACEDFROM EACH OTHER, A PAIR OF SUPPORTING CROSS ARMS POSITIONED TRANSVERSELYBETWEEN SAID STRUTS, MEANS FOR ATTACHING SAID ARC TUBE TO SAIDSUPPORTING CROSS ARMS AND MEANS TO POSITION SAID HARNESS IN A BULBOUSENVELOPE.